Dr Tina Bell
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Potential PhD/Honours Projects |
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Please contact Tina to discuss project topics
- Nitrogen:phosphorus ratio in foliage – do Australian heathlands and woodlands conform to global trends?
- Allometric relationships between tree size and age for Stringybark (Eucalyptus baxteri)
- Investigation of seed banks from long unburnt Callitris woodland
- Leaf anatomy of alpine grass species
- Soil seed banks as indicators of fire management strategies
Nitrogen:phosphorus ratio in foliage – do Australian heathlands and woodlands conform to global trends?
A number of global syntheses have recently been completed for foliar N:P ratio and some distinct patterns have emerged. For example, trees produce less biomass per unit N or P than small shrubs. The slope of the N:P relationship in the global data set is less for conifers and shrubs than for trees or grasses and herbs. However, one of the major problems is that representation of the Australian flora in these data sets is limited. Development of a data set of N:P ratios of foliage from a range of plant species from heathlands and woodlands in south-east Victoria will allow broad comparison of nutrient allocation patterns with vegetation elsewhere in the world. This project will involve fieldwork for collection of samples, some chemical analysis and collation of data from other sources (published and unpublished).
Allometric relationships between tree size and age for Stringybark (Eucalyptus baxteri)
There is good evidence emerging from our current research that fire frequency has an impact on tree size class distribution in Heathy Stringybark woodlands. We don’t know if this is due to the elimination of trees by fire or other disturbance or through suppression of growth. In this project you will develop a relationship between tree size (diameter at breast height and tree height) and tree age by taking a series of cores from a range of trees and attempting to count the number of growth rings. Using fire history records and growth rings from understorey shrubs (particularly Desert Banksiaor Banksia ornata) you would also attempt to cross-correlate tree ring numbers with time since fire. As additional evidence, you will survey a recently burnt area for germination of eucalyptus seedlings. This project will provide important information about tree recruitment and stand structure and will involve field work near Casterton and preparation and examination of wood samples using light microscopy.
Investigation of seed banks from long unburnt Callitris woodland
Staged prescribed burning is planned for an area of long unburnt Callitris woodland near Mildura. It is unknown what the seedbank is like and what species are likely to germinate after fire as only a thick overstorey of Callitris and few understorey species are currently present. Land managers do not know when or how they should burn to promote greatest post-burning plant diversity. Germination trials of composite seedbank samples incorporating a number of treatments (e.g. heat, smoke water) will help to predict what species are likely toappear after fire. Species identified from seedbank studies will then be compared to databases of surrounding vegetation. This project will assist land managers to determine what type of prescribed fire (season of burn, intensity, size, patchiness) should be applied.
Leaf anatomy of alpine grass species
Current landscape-scale research has identified the need for in-depth knowledge of leaf anatomy of alpine grass species including Poa hiemata (Snow grass), P. costiniana (Prickly Snow grass), Danthonia alpicola, D. nudiflora (Alpine Wallaby grass) and Chionochloa frigida (Ribbony grass). These species represent important components of alpine ecosystems including alpine grasslands and heathlands and as understorey species of Snowgum woodlands. The leaves of both species of Poa are normally rolled making it difficult to interpret photosynthetic measures made using leaf chambers and conventional methods of leaf area assessment (e.g. leaf area meter) is not possible. Anatomical studies of leaves and measures of photosynthetic area will help in interpreting physiological measures and will feed into models of carbon balance in alpine regions of eastern Australia. In addition, whole plant biomass (living leaves versus dead leaves) will be determined. This project will involve field work in Victoria and New South Wales for collection of plant material, microscopy and development of taxonomic skills.
Soil seed banks as indicators of fire management strategies
Although there is considerable information on many of the vital attributes of plants, there is a critical knowledge gap in the role of soil seed banks in species persistence. Existing research on soil seed bank persistence in relation to fire is limited. The focus has mainly been on germination treatments and cues rather than seed longevity. By studying a number of species of differing sensitivity to different fire regimes, especially obligate seeders, generalisations can be drawn on plant functional types. This information will help refine the minimum and maximum intervals for prescribed burning in vegetation where these plant functional types occur. Sites will be chosen to represent a variety of fire histories and variables may include fire interval, season, intensity and frequency. This research will enable the refinement of current vital attribute information on the target species, and hence adjustments to the recommended minimum and maximum fire intervals for the Ecological Vegetation Classes and Divisions (EVCs and EVDs) in the study area.